This invention relates to seat recliner mechanisms and, more particularly, to such devices adapted for motor vehicle applications which permit the angle of the seat back relative to the seat bottom to be varied in accordance with the desires of the seat occupant.
Many motor vehicles are now being provided with seat recliner mechanisms which provide added comfort and convenience for the vehicle occupants. Numerous types of seat recliner mechanisms are known according to the prior art. For example, U.S. Pat. No. 4,372,610, issued to A. J. Fisher, III, et al on Feb. 8, 1983, describes a recliner employing a pair of meshing straight toothed racks. One of the racks is connected to the upper recliner structure through a quadrant component. Adjustment of the seat reclined position is accomplished by changing the meshed position of one rack with respect to the other.
Although seat recliner mechanisms according to the prior art perform satisfactorily, it is desirable to provide a seat recliner mechanism having a redundant system for controlling the position of the seat back, thereby preventing unrestrained movement of the seat back in the event of the mechanical failure or improper operation of a recliner component.
The above features for a motor vehicle seat recliner mechanism are provided in accordance with the invention by employing a curved toothed rack on a component which rotates with the upper recliner structure and which meshes with a recliner gear that is rotatable within the lower recliner structure. The seat back and bottom are connected to the recliner upper and lower structures respectively. Locking of the seat back may be achieved in any number of ways, for example, by causing teeth of a locking pawl to engage the gear. Adjustment of the seat back angle is provided when the locking pawl is withdrawn from engagement with the gear, thereby permitting gear rotation as the upper recliner mechanism and the seat back rotate about their pivot points. Further, a restraint pawl is provided which prevents uncontrolled movement of the upper recliner structure in the event that the recliner gear, locking pawl or other related component fails.
The recliner mechanism according to this invention is usable for motor vehicle seats which are installed in two or four door type vehicles. In four door models, the front seat back does not need to be folded forward to permit access to the rear seat occupant area. However, in two-door designs having a rear seat occupant area, such provisions are necessary. This invention is described in conjunction with an inertia sensitive seat back locking device according to prior art designs which normally permits seat back folding but acts to prevent folding when the vehicle is subjected to deceleration above a predetermined level. The benefits and advantages of this invention are, however, equally applicable to seat recliners which do not have inertia sensitive seat back locking systems such as those intended for two-door car applications.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.